Railway traffic controlling apparatus



May 30, 1939. P. N. BOSSART RAILWAY TRAFFIC CONTROLLING APPARATUS 4 Sheets-Sheet l INVENTOR 0550x1 1. BY

H15 ATTORNEY $5 Paul Filed March 26, 1938 May 30, 1939 P. N. BOSSART RAILWAY TRAFFIC CONTROLLING APPARATUS Filed March 26, l938 4 Sheets-Sheet 2 a-fl- INVENTOR Paul N 03301 1.

U .R N W 111s ATTORNEY May 30, 1939. P. N. BOSSART RAILWAY TRAFFIC CONTROLLING APPARATUS Filed March 26, 19:58

4 Sheeis-Sheet 3 i Q w s? w p m @R u mm N S R E 0 O Q M m w Wm u d m L W W L 8w Y \WQN m QQV 6N v a B H w I w w NNN EW T WQ 3% Ti Q L 3N A Avg mg wQ @QN mg 5 N g Q I My mg 8N NS May 30, 1939. P. N. BOSSART RAILWAY TRAFFIC CONTROLLING APPARATUS Fiied March'26, 1938 4 Sheets-Sheet 4 mwo @ D QQQ INVENTOR Paul Wsscmz. BY HIS ATTORNEY Patented May 30, 1939 UNITED STATES PATENT OFFICE RAILWAY TRAFFIC CONTROLLING APPARATUS Application March 26, 1938, Serial No. 198,299

20 Claims. 24663) of cab signal indications which are obtainable from a restricted variety of trackway current codes.

A further object is to accomplish the above by relatively simple additions to and without funda- 20 mental changes in the equipment of existing systems of coded cab signalling.

In the practice of my invention, the above and other objects and advantages are attained by utilizing train-control energy of only the usual number (ordinarily 2 or 3) of different rates of coding or modulation. Instead, however, of employing the energy as coded at one or another of these individual rates only, I also selectively supply the running rails with composite energy 30 which is coded simultaneously at two or more of the rates. Then, by arranging the traincarried indicating means to respond distinctively to energy of each of the composite codings as Well as to energy of each of the individual cod- 35 ings, a corresponding extension in the number of cab-signal aspects or indications is at once obtained.

I shall describe two forms of railway traffic controlling apparatus embodying my invention,

m and shall then point out the novel features thereof in claims. These illustrative embodiments are disclosed in the accompanying drawings in which:

Fig. 1 is a diagrammatic representation. of the 5 trackway portions of a four-indication cabsignalling system which incorporates the improvements of my invention;

Fig. 2 is a diagrammatic representation of the three distinctive forms of energy which the way- 50 side apparatus of Fig. 1 supplies to the track- Fig. 3 is a diagrammatic view of the traincarried portions of the four-indication cabsignalling system referred to in connection with Fig. 4 is a representation of the apparatus of Fig. l modified to include circuits for shunting the inactive track transformer over relay contacts;

Fig. 5 is a diagrammatic representation of the 5 trackway portions of traffic-controlling apparatus which is organized in accordance with my invention into an eight-indication system of cabsignalling;

Fig. 6 is a showing of ,four of the seven dis- 10 tinctive characters of energy which the wayside apparatus of Fig. 5 supplies to the trackway; and

Fig. 7 is a diagrammatic View of the traincarried portions of the eight-indication cabsignalling system referred to in connection with Fig. 5.

In the several views of the drawings, like reference characters designate corresponding parts. Referring first to Fig. 1, characters I and 2 designate the rails of a track over which it will be assumed that traffic moves in the single direction indicated by the arrow, or from left to right in the diagram. Insulated rail joints 3 divide the protected stretch of this track into the customary successive sections or blocks, only two of which, DE and E-F, are completely shown, and the rails of each of these sectionsform a part of a track circuit of the usual character.

Each of the track circuits further includes the operating winding of a track relay TR connected to the rails thereof at the entrance end of the section and energy supply facilities also connected to the rails but at the opposite or exit end of the section. The particular facilities shown include a direct current source in the form of a track battery 4 and also an alternating current source designated by the terminals B and C. To facilitate later explanation, it will be assumed that the voltage of source B-C has the usual signal-power frequency of 100 cycles per second and that trackway energy derived therefrom is effective to control cab signalling equipment carried upon a train when within the track section.

Each of the track relays shown at TB is ofa three-position polarized type and is designed to respond to direct current energy which the battery 4 supplies. This energy is transmitted to each of the track circuits through a circuit which includes the usual current-limiting impedance 7 and pole-changing contacts 5 and 6 of the track relay TR. which is associated with the next track section in advance. As long as the winding of the relay is deenergized (as in the event that the 5 rails of the associated track section are shunted by a train), the contacts occupy their mid or released position in which they connect the track battery 4 to the rails of the rear track section in reversed-polarity relation (the negative terminal to rail I through contact 5 and the positive terminal to rail 2 through contact 6) When, however, the relay winding receives such reversed polarity energy, the contacts are shifted to their right or reversed position and the rails of the rear track section then are connected with the battery 4 in normal-polarity relation (rail I to the positive terminal through contact 5 and rail 2 to the negative terminal through contact 6). Similarly, when the relay receives such normal polarity energy, it shifts its contacts to the left-hand or normal position in which they again connect the track rails in normal-polarity relation with the supply battery 4. Moreover, upon each deenergization of the winding of the relay, the contacts thereof return to their mid or released position first described above.

In consequence, whenever a train occupies one of the track sections and deenergizes the associated track relay it causes the battery 4 controlled thereby to supply reversed polarity energy to the rails of the track section to the rear; this energy causes the relay TRat the entrance end of that section to hold its contacts in the right position in which the associated battery 4 supplies normal-polarity energy to the rails of the second section behind the occupied one; this normal-polarity energy causes the track relay at the entrance end of the second section to hold its contacts in the left or normal position in which the rails of the third section behind the occupied one are supplied with normal energy; and so on.

The just-described direct current from battery .4 is the only energy which is supplied to the rails of each track section as long as the section remains unoccupied. When, however, a train comes into the section, coded alternating current energy from source BC is also impressed upon the rails thereof. This results from a completion by a track relay contact 9 of the energizing circuit (shown as including a line conductor 8 and supply terminals plus and minus) for an approach relay AR at the opposite or exit end of the section and the respective actions of contacts In and I I of that approach relay in placing in operation a code transmitter CT and in setting up circuits through which one or the other of two contacts 80 and I8!) of device CT may periodically connect the alternating current source BC to the primary winding of one or the other of a pair of track transformers T80 and Tl80.

Each of the transmitting devices CT includes a motor or other suitable mechanism (not shown in detail) which, during operation of the transmitter, continuously actuates the two contacts 80 and I80 thereof at two different speeds which, for purposes of explanation, will be assumed to be such as respectively to provide codes of 80 and 180 energy pulses per minute. Atcertaintimes, which are determined by the contact positions of the-associated track relay TR and also those of an associated orauxiliary control relay SR, coding contact 80 is included in the primary winding circuit of the track transformer T80 and at other times contact I 80 is similarly included in the primary or energy-supply circuit for the second track transformer TIBU.

The secondary windings of the two track transformers are series connected in the railsupply circuit previously described as including the impedance 1 and the track battery 4. As long as both transformers are deenergized and the track rails receive only direct current energy from the battery, the transformer secondaries serve merely as conductors in the rail circuit. To reduce the impedance which one secondary winding presents to alternating current from the other secondary winding when the primary of the transformer is open at the contacts of TR, SR or CT, it is preferable to bridge each of them by a resistor or other suitable shunting path l2. This bridging element is so proportioned that it pre- Vents the transformer from introducing an objectionable amount of impedance in the rail supply circuit when inactive and yet does not substantially interfere with an introduction of alternating current energy into the rail supply circuit when the transformer is active.

Each of the previously mentioned auxiliary control relays SR is of a direct current two-position type and receives operating energy (from a suitable source again designated by the terminals plus and minus) over a line conductor I4 from the second section dividing location in advance and under the control of a contact l5 of the track relay TR at that advance location. As long as the advance track relay remains energized the winding circuit for relay SR is completed and th contacts thereof then occupy their picked-up position. When, however, the advance track relay becomes deenergized, as when the second track section ahead is occupied, the contacts of the auxiliary control relay SR at the rear location occupy their lowermost or released position.

In considering the manner in which the coded energy supply circuit operates in the wayside system of Fig. 1, first let it be assumed that all of the sections of the protected stretch of track are vacant. In this event all of the track relays TR receive direct current energy of the normal polarity, all of the auxiliary control relays SR hold their contacts in the energized position, and all of the approach-control relays AR maintain the associated code transmitters CT inactive.

l When, now, a train advancesthrough the track stretch, the shunting action of its wheels and axles deenergizes thetrack relay associated with each of the occupied sections, the approach relay AR at the exit end of the section places the code transmitter CT into operation and the rails of the section are accordingly supplied with alternating current train-control energy of a character which is determined by the advance traffic conditions.

If at least three track sections ahead of the occupied one are vacant, this energy is of the 180 code. only as a result of the contacts of relay TR at the exit end of the blockbeing in their left .or normal position and those of auxiliary control relay SR being in theirpicked-up position. The circuit through which theprimary winding of the track transformer TIBD receives energy under these, conditions may be traced from the alternating current supply terminal B, through front contact H of.relay.AR,,conductor H, the coding contact I80, conductor.l8,-front contact I 9 of relay SR, conductor 20, normal contact 2| of relay TR, conductor 22, the primary of transformer Tl80 and conductors 23 and 24 back to the terminalC of thealternating current supply source.

If an advance train, diagrammatically indicated at V in Fig. 1, is in the third track section LII ahead of the following train, the rails of the track section through which this following train is advancing simultaneously receive energy of both the 180 and the 80 codings as a result of the contacts of the track relay TR at the exit end of that section being to the left and those of the auxiliary control relay SR being released, as shown at location D in Fig. l. The supply circuit for transformer TI80 may now be traced from the supply terminal B through front contact I l of relay AR, conductor I'I, coding contact i88, conductor l8, back contact I9 of relay SR, conductor 20, normal contact 2| of relay TR, conductor 22, the primary of transformer Tl80 4 .and the conductors 23 and 24 back to the supply terminal C. The circuit through which the second track transformer T80 simultaneously is energized may be traced from the supply terminal B through front contact ll of relay AR, conductor ll, coding contact 80, conductor 26, back contact 21 of relay SR, conductor 28, normal contact 28 of relay TR, conductor 30, the primary of transformer T80 and conductor 25 back to the supply terminal C.

If only one track section ahead of the following train is vacant the rails of the section through which that following train is advancing receive energy of the 80 coding only as a result of the contacts of the track relay TR at the exit end of that section occupying the right or reversed position and those of the auxiliary control relay SR occupying the picked-up position, as shown at location E in Fig. 1. The circuit through which the primary of transformer T80 now receives energy may be traced from the supply terminal B through front contact ll of relay AR, conductor ll, the coding contact 80, conductor 26, front contact 3| of relay SR, conductor 33, reversed contact 34 of relay TR, conductors 35 and 30, the primary of track transformer T80 and conductor 24 back to the supply terminal C.

Finally, if the section immediately ahead of that being passed through by the following train is occupied by an advance train, the trackway does not receive coded energy of any character as a result of the contacts of the track relay TR at the exit end of the section occupying the mid or released position indicated at location F in Fig. 1. When the relay apparatus has this condition, the primary energizing circuits for both of the track transformers T80 and Tl80 are broken by these track relay contacts.

From the foregoing it will be seen that, depending upon advance trafi'ic conditions, the wayside apparatus of Fig. 1 at each of the section dividing locations D, E, F, etc. is effective to supply the trackway with energy of one or another of the three different characters which are represented in Fig. 2. In considering the diagrams of this figure, it will be appreciated that each of the simplified trackway-energy representations thereof typifies a group of 100 cycleper-second alternating current waves which are supplied from the source BC through a contact of the coding device CT.

From Fig. 2 it will be evident that the energy of each of the !80 and 80 codings is of conventional character and when such is supplied to the trackway individually the effect is comparable to that previously known. In the case, however, of the simultaneous introduction into the track circuit of energy of both of the I80 and 80 codings, the distinctive composite character of energy indicated in the lower portion of Fig. 2 results. Because of the fact that the secondaries of the two track transformers T80 and TI80 are connected in series, the energy which they simultaneously supply is additively related and in consequence the resulting blocks of trackway energy have the peculiar shape indicated.

The trackway apparatus of Fig. 1 having been described, attention will next be directed to the cooperating train-carried cab-signalling equipment of Fig. 3. As has been stated, this equipment is of the four-indication variety and is arranged to give a distinctive response when the train by which it is carried advances along the running rails l and 2 and receives energy of the I80 coding, of the 80 coding, of the composite 80l80 coding, and uncoded energy or no energy at all.

This equipment of Fig. 3 converts a measure of the coded energy present in the track rails into appropriate train controlling indications aboard the locomotive or other train vehicle which carries the equipment. It includes a receiver 35-31, a filter 38, an amplifier 39, a master transformer MT, a pair of modulation amplifying tubes 4| and 42, a decoding transformer DT, a pair of decoding relays DR and an indication-giving cab signal CS.

The receiver may be of conventional design consisting of a laminated iron bar 36 mounted ahead of the advance truck of the locomotive just above and spanning the two running rails and carrying windings 31 in which voltages are induced upon the flow of alternating current in the rails from a point ahead of the train. The filter 38 likewise may be of conventional design. As is more completely represented in Fig. 7, it consists of capacitor and reactor elements so interconnected and proportioned as to suppress all frequencies except that of the 100 cycle or other selected trackway energy carrier wave value.

The amplifier 39 is controlled by the output potential of the filter and it functions in the usual manner to deliver an appropriately increased amount of operating energy to the mas ter transformer MT. In the illustrative form shown in Fig. '7, this amplifier includes a tube 43 which strengthens the energy in the form in which it is received from the filter and a detector tube M which rectifies the individual waves of alternating current in each pulse of the received trackway energy and thus passes on to the master transformer MT only a strengthened measure of the modulation or coding of this energy.

The coupling between the carrier wave amplifying tube 43 and the modulation detecting tube 44 is shown in Fig. '7 as being of a conventional reactance type. Use also is made of a capacitor 45 which functions to absorb the current peaks and to store the energy of the individual half cycles of carrier wave current in a manner that each code pulse of trackway energy causes the primary current of the master transformer MT gradually to build up and then again gradually die down at the end of the pulse. The necessary high voltage potential for operating the plate circuits of the electronic tubes is shown as being supplied from a source 550, with which terminal markings minus h and plus h are identified. Likewise, current for lighting the filaments of the tubes is shown as being supplied from a source 32 of lower potential (such as the locomotive headlight generator) through a circuit which includes all of the tube filaments in series and which is arranged to provide the necessary gridbiasing potentials.

The amplifier tubes 4i and 42 interposed between the transformers MT and DT are connected in push-pull relation. Normally, or as long as uncoded energy is not being received from the trackway, direct current from the supply terminal plus h flows from the mid tap 46 of the primary of transformer DT in equal intensity upwardly through the upper half of the winding and downwardly through the lower half of the winding. Tube 4| completes the circuit path for the current first named, tube 42 completes the path for the current last named, and each of these currents returns to the supply terminal minus h by way of the tube filament 41. The mentioned equal nature of these currents results from the fact that under the conditions stated the master transformer MT supplies zero out-put and thus does not alter the normal biasing potential (represented in Fig. 3 as originating in a battery 48) impressed upon the grids 49 of the push-pull tubes. As long, therefore, as the stated condition continues the opposing primary currents of the decoding transformer DT neutralize each other and the net flux and hence out-put voltage of this transformer accordingly remains zero.

Upon the occasion, however, of each pulse of coded energy which is received from the track- Way, the secondary winding of the master transformer MT has induced therein a positive half cycle of alternating current voltage at the beginning of the pulse and a negative half cycle of voltage at the ending of the pulse. In each instance the grid bias of one of the push-pull tubes is changed in one direction and the grid bias of the other tube is changed in the opposite direction, due to the mid tap 50 of the secondary of transformer MT being electrically connected to the filament 41 of both tubes and the opposite ends of the secondary winding being connected to the tube grids 49. In consequence, as the impedance of the current path between the anode and cathode elements 52 and 41 of one of the tubes is raised, that of the other tube is lowered, and vice versa, and in this manner the rectified measure of the trackway energy modulation is repeated from transformer MT into the decoding transformer DT in highly amplified forms.

From a standpoint of operation, the resultant effect upon transformer DT offers all of the advantages of that produced by mechanically pole changing at code frequency (as by the aid of movable contacts carried by the usual code-following master relay) the direct current primary circuit of that transformer. In addition, the electronic tubes herein disclosed possess the further advantage of being able to follow the relatively complicated changes caused by two or three codes being superimposed one upon the other in the track circuit. That is, at the beginning of each of the received pulses of coded trackway energy, regardless of whether present in the trackway individually or in combination, current through one half of the primary winding of transformer D1 is increased and that through the other half is decreased, and at the end of each of the pulses the current through the first half of the winding is decreasedand that through L the second half of the winding is increased.

o n Q t e r ckwe n r ybr wh h he primary current vfluctuation's are initiated. Inthe particular system disclosed in Fig. 3, this secondary voltage thus will have a frequency of 80 cycles per minute, of 180 cycles per minute, or of a superposed combination of both of those rates.

Because of the fact that the push-pull primary of transformer DT normally gives no net direct current in the core, the effective permeability of the core is considerably higher than if the pushpull arrangement were not used. In applications of the type herein shown this is especially important because with frequencies of the low order which it is desirable to use, very large values oi inductance are necessary to make an eificient transformer.

The out-put or secondary voltage of the decoding transformer DT constitutes the source of operating energy for the decoding relays DR which control the cab signal CS. The relay energizing circuits are of a conventional tuned type and in the particular arrangement shown each includes a full wave rectifier 55. In the case of relay DR|80 the rectifier supply circuit includes a reactor 56 and a capacitor 51 which are so interrelated as to pass enough current to actuate the relay only when energizing pulses of the I80 code frequency are received from the transformer In the case of relay DR80 the circuit includes a capacitor 58 and a reactor 59v designed to be resonant at the 86 code frequency and to energize the relay only when the decoding transformer passes energy pulses at the rate of 80 per minute.

The previously mentioned control of the cab signal CS by the decoding relays DR is effected through the medium of contacts 62, 63 and 64 carried thereby and so arranged that their positional combination determines whether a lighting circuit is completed for one or another of the four lamps A, R, L and S of the signal unit. Lighting current for these lamps may, of course, be supplied from the locomotive headlight generator or any other suitable source designated in the diagram by the terminals plus" and [lminusI,-

Whenever energy of the I80 coding only is being received from the trackway, decoding relay DRl8fl only receives actuating current in an amount sufficient to pick up its contacts. Under this condition cab signal lamp A receives lighting current over a circuit which extends from a positive supply terminal through front contact 62 of relay DRI8U, conductor 65,'back contact 63 of relay DR80, conductor 66, the lamp A and conductor 61 back to the negative supply terminal.

Likewise, when trackway energy of the 80 code only is being received the contacts of relay DB8!) only are picked up. Under this condition cab signal lamp L receives lighting current over a circuit which extends from the positive supply terminal through back contact 62 of relay DRl8ll, conductor 68, front contact 64 of relay DRBU, conductor 69, the lamp L and conductor 61 back to the negative supply terminal.

In the event t at, no coded energy is received from the trackway neither of the relays DR receives actuating current and the contacts of both then accordingly occupy the released position. Under this condition, cab signal lamp S rece s i ht curr n ov r c rc t. w ch extends from the positive supply terminal through back contact 62' of relay DRI80, cone d ster fi l, back contact .64 of re ay DR. 1-

ductor H, the lamp S and conductor 61 back to the negative supply terminal.

Finally, in the event that energy of the composite 8DI80 code represented in the lower portion of Fig. 2 is received from the trackway, both of the decoding relays DRIBO and DRBI] receive from transformer DT sufficient energizing current to effect their actuation and the contacts of both are accordingly held in the pickedup position. Under this condition lamp R of the cab signal CS receives lighting current over a circuit which extends from the positive supply terminal through front contact 62 of relay DRIBO, conductor fiii, front contact 63 of relay DRBI], conductor 12, the lamp R and conductor 61 back to the negative supply terminal.

In effecting this just described fourth indication, the improved decoding equipment of my invention responds simultaneously to the modulation frequencies of both of the 80 and I80 codes which are simultaneously supplied to the trackway by the apparatus of Fig. 1. Even though the magnitude of the trackway energy is at times double that which is present when only one of the two codes is supplied individually, the modulations of both of the codings when additively combined as shown at the bottom of Fig. 2 are as accurately transmitted to the train-carried decoding apparatus and. as: positively responded to by as when each of the codes is received individually. This comes about from the fact that the push-pull amplifier tubes H and 42 are caused to vary their impedances and hence to alter the primary current of the decoding transformer DT upon each change in energy level regardless of whether that change is with respect to the usual zero reference line or with respect to some other reference line identified with an intermediate energy level.

The manner in which the complete cab signal system of Figs. 1-3 operates to provide four distinctive indications aboard the train will have become evident from the preceding description of the operation of the trackway portions of Fig. 1 and of the train-carried portions of Fig, 3. As long as three full track sections or blocks ahead of the signal carrying train are vacant, the rails of the section through which the train is proceeding receive energy of the I80 code only and lamp A of the train-carried signalCS is caused to light under the control of the received measure of that energy; when there are only two vacant blocks ahead, the track rails simultaneously receive energy of both the I89 and the 80 codings and lamp R of the cab signal is thereby caused to light; when there is only one vacant block ahead, the track rails are supplied with energy of the 80 coding only and lamp L of the cab signal is then lighted; and finally when the track section immediately ahead of that through which the signal carrying train is proceeding is occupied, or when the signal carrying train is in the same section as the advance train, no coded energy is received from the trackway and cab signal S is then lighted.

In describing the trackway apparatus for the four-indication cab signalling system of Figs. 1-3, it was pointed out that the resistors which are shown at I2 in Fig. 1 as by-passing the secondary windings of the track transformers T80 and Tliill perform the function of reducing the secondary impedances of the transformers when the primary windings thereof are inactive and open circuited.- This impedance reduction is, of course, essential because of the series connection of the two transformer secondaries in the rail-supply circuit. In instances where the presence of the by-passing resistors I 2 may be objectionable because of the power which each consumes under conditions of energy supply on the part of the associated track transformer the equivalent expedient disclosed in Fig. 4 may instead be used.

Referring to Fig. 4, it will be seen that the trackway apparatus there represented is a duplicate of that shown at each of the, section dividing locations D, E, F, etc. of Fig. 1 with the exception of the fact that the transformer bypassing resistors I2 are eliminated and in place thereof the primary winding circuit for each of the track transformers is arranged to be closed upon itself through one or more relay contacts whenever that circuit is not active in transmitting trackway energy. Because of the resulting short circuit of the primary winding of each track transformer when thus inactive, the impedance to a flow of current through its secondary winding is reduced to the comparatively low value sufiicient to assure satisfactory operation of the trackway energy supply facilities.

For providing this short circuiting, the apparatus of Fig. 4 makes use not only of the contacts of the track relay TRand those of the auxiliary control relay SR but also of the coding contacts 80 and IBI] of the device CT. These coding contacts, however, effect the by-passing function only when both of the BB and I8!) codes are simultaneously being supplied, and they then do this through the medium of backpoints 13 and 1'4 with which capacitors .15 and 16 are associated for a purpose later to be made evident.

The exact nature of these modified transformer supply circuits may best be explained by describing the various current paths which are active under various conditions of operation of the wayside equipment of Fig. 4. Assume first that energy of the 80 coding is being supplied individually as a result of the contacts ofthe track relay TR occupying the right position and the contacts of the auxiliary relay SR being picked up. The circuit through which track transformer T8!) then receives the coded energy pulses may be traced from the supply terminal B through front contact II of relay AR, conductor ll, coding 'contact 80 of device CT, conductor 26, front contact 3| of relay SR, conductor 33, right contact 34 of relay TR, conductor 30, the primary of transformer T80 and conductor 24 back to the supply terminal 0. Under this condition of individual supply of the 80 code energy, the primarywinding of the inactive track transformer TI 8!! is continuously by-passed over a circuit which extends from the right terminal of the winding through conductor 22, right contact 2| of relay TR and conductors 11, 24 and 23 back to the left terminal of the transformer winding.

Assume next that the trackway is being supplied with energy of the I80 coding only as a result of the contacts of relay TR occupying the left position and those of the auxiliary relay SR again being picked up. The circuit through which the primary winding of transformer T|80 is periodically connected with. the supply source BC may be traced from the supply terminal B through front contact I l of relay AR, conductors I1 and 19', coding contact I89, conductor 18, front contact 19 of relay SR, conductor 20, left contact 2! of relay TR, conductor 22, the primary of transformer TIBO and conductors 23 and. 24

back to the supply terminal C. Under this conboth of the track transformers T80 and TI80 areactive and the primary winding of each is bypassed only during the period that energy is not being transmitted through that winding. In the case of transformer T80, this by-passing is effected by the coding contact 80 of device CT aided by back point 13 and the capacitor I5 associated therewith, and in the case of the primary of transformer TI 80 the shunting action is ef' fected by means of coding contact [80 cooper ating with back point 74 and being aided by the capacitor I6. As will be seen, these capacitors are, under the particular conditions now being considered, directly bridged across the associated transformer windings and they thus serve to prevent voltage rise there across during the time that the coding contacts move from the front or energy-supplying position to the back or winding by-passing position. c I

As in the system of Fig. 1 (of which it has been seen that the trackway apparatus of Fig. 4'constitutes a counterpart), this composite till-I80 train control energy is supplied to the running rails when the contacts ofth'e track relay TR occupy the left or normal position and those of the auxiliary relay SR occupy the lowermost 'or released position. Considering first the action of the 80 coding contact of device CT, each time that it is in its uppermost orfro'n't position it corrnects the primary winding of transformer T80 with the supply source B--C over a circuit which extends from the supply terminal B through front contact II of relay AR, conductor ILcoding contact 80, conductor 25, left contact 29 of relay TR, conductor 28, back contact 2'I of relay SR, conductor 18, left contact 34 of relay TR, conductor 30, the primary of transformer T80 and conductor 24 back to the supply terminal 0. Each time that the coding contact 80 occupies its lowermost position it by-passes the primary winding of transformer T80 over a circuit which extends from'the right terminal of the winding through conductor 30, left contact 34 of relay TR, conductor 18, back contact 21 of relaySR, conductor 28, left contact 29 of relay TR, conductor 28, coding contact 80 and 'asscciated back point 13, and conductors 82 and 24 back to theleft terminal of the transformer winding.

Considering next the action of the coding contact I80, each time that it occupies its uppermost .position it connects track transformer TI80 with the supply source B-"C through 'a'circuit extending from supplyterminal B through front contact II of relay conductors I1 and "I3, coding contact I80, conductor I8, back contact I9 of relaySR, conductor 20, left contact ZI of relay, TR, conductor 22, the primary of transformerTI80 and conductors 23 and 24 back to the supply terminal C. Each time that thecoding contact I80 is in its lowermost position it bypasses the primary winding of track transformer TI80 by completing a circuit which extends from the right terminal'of the transformer wi'n'ding through conductor 22, leftcontact 2| or relay TR, conductor 20, back contact I9 of relay SR, conductor I8, the contact I80 and cooperating back point I4, and conductors 24 and 23 back to the left terminal of the transformer winding. 7 n

During the composite coding supply operations just described, it will be seen that the capacitors I5 and 16 are at all times connected in parallel with the primary windings of transformers T80 and TI80, respectively. As has been mentioned, theyrestrict the voltage rise across the winding during the short periods that the coding contacts 80 and I80 are changing their positions. Since the capacitors" are practically Wattless, no extra to hold its contacts in the front position, both of i the track transformers T80 and TI80 are disconnected from the supply source B-C. Preferably, though not necessarily, the primary windings thereof are then again continuously short circuited. In the case of transformer T80 the represented by-passing path which is effective under the conditions stated extends from the right terminal of the winding, through conductor 30, released contact 34 of relay TR, conductor 18, front contact 21 of relay SR, and conductors I1 and 24 back to the left terminal of transformer winding. In the case of the transformer TI80 a similar primary shunting circuit is shown in Fig. 4 as extending from the right terminal of the winding, through conductor 22, released contact 2| of relay TR, and conductors TI, 24 and 23 back to the left terminal of the winding.

Considering how the cab signalling system of Figs. 5-7, in principle and in operation it is basically similar to thejust described four-indication system of Figs. 1-4. It differs therefrom, however, in including provision for the giving of a total of eight distinctive indications by the cab signal CS8, which forms a part of the apparatus of Fig. 7, and for selectively supplying the running rails with train-control energy of three different codings individually and with four different composite combinations thereof.

Referring first to the trackway apparatus of Fig. 5, characters I "and 2 there designate the rails of a track which is adapted for single-direction running, character 3 the insulated joints which divide these rails into the usual consecutive track sections, characters M and N two of the section-dividing locations, and character TR the track relay which is installed at the entrance end of each of the track sections. As in the case of the trackway'apparatus of Fig. 1, the track relays TR are of the polarized direct current three-position type and the winding of each receives operating energy through the'rails of the associated section from a track battery 4 installed at the opposite or exit end thereof.

The three individual codings' of train-control energy which'have been mentioned are respectively produced by contacts 60, I20 and 200 of coding devices CT3 which, with the exception of having a larger number of contacts, may be duplicatesof the devices CT of Fig. 1. These three coding contacts modulate the supply of energy from the alternating current source BC to associated track transformers T60, TI20 and T200 at rates which will be assumed to produce codes of 60, 120 and 200 energy pulses per minute, respectively. As shown, devices GT3 are controlled by approach relays AR in the same manner as has been explained in connection with Fig. 1.

As in the case of the two-transformer arrangement of Fig. 1, the primary windings of the three track transformers T60, TI20 and T200 of Fig. 5 are arranged for parallel connection while the secondary windings thereof are connected in series in the rail-supply circuit of which the track battery 4 and the current limiting impedance 1 form a part. Bridging the secondary windings of these transformers are resistors or other impedance devices I2 the action of which in reducing the secondary winding impedance is the same as that already explained in connection with Fig. 1. If desired, of course, these may be replaced by circuits, of the character shown in Fig. 4, which operate to by-pass' the primary windings of the transformers whenever these windings are not employed in transmitting energy to the trackway.

The circuits through which the coding contacts 60, I20 and 200 establish connection of the primary windings of the associated track transformers T with the supply source BC are set up individually and in various combinations by the contacts of the track relay TR and those of an associated or auxiliary control relay SR3. This auxiliary relay is comparable to the two position relay SR of Fig. 2, but differs therefrom in that its contacts are adapted to occupy one or another of three different positions in accordance with whether the relay winding receives normal polarity current, reversed polarity current, or no current at all.

In the illustrative arrangement shown this winding current originates in a battery and is transmitted to the Winding over conductors 86 and B1. The presence or absence and the polarity of this current is determined by the setting of a three position switch 8990. When the blades of this switch occupy the left-hand or normal position represented, conductor 89 is positive with respect to conductor 81 and the winding of relay SR3 is energized in a manner which actuates the contacts to the left or normal position. When the switch blades occupy the central position the battery 85 is disconnected from the relay winding and the contacts of the relay then are released to the central or mid position. Finally, when the blades of the switch occupy the right-hand or reversed position, the relay SR3 actuates its contacts to the right or reversed position.

To simplify explanation it will be assumed that the track relays TR of the system of Fig. 5 re spond in the same manner as do the similarly designated devices of the four-indication trackway equipment of Fig. 1. Under certain conditions, therefore, the contacts of each of the relays TR occupy the left or normal position represented, under other conditions they occupy the central or released position, and under still further conditions they occupy the right-hand or reversed position.

The manner in which the contacts of relays TR and SR3 cooperate to set up the energizing circuit for the three track transformers T90, TI 20 and T200 may best be explained by tracing the circuits through which these transformers receive periodically interrupted energizing current under various conditions of operation of the trackway equipment of Fig. 5. When the contacts of both of the relays TR and SR3 at one of the locations M, N, etc. are to the left, the associated track transformer T200 only is active and the rails of the track section to the rear then receive energy of the 200 coding only over a circuit which. extends from supply terminal B through frontcontact II of relay AR, conductor I'I, coding con tact 290 of device GT3, conductor 92, left contact 93 of relay SR3, conductor 94, left contact of relay TR, conductor 93, the primary of transformer T200, and conductors 91 and 98 back to the supply terminal C.

When the contacts of relay TR are to the left and those of relay SR3 are to the right, the track transformer TI20 only is active and the rails of the associated track section then receive energy of the I29 coding only over a circuit which extends from the supply terminal B through front contact II of relay AR, conductor I'I, coding contact I29 of device GT3, conductor 99, right contact I00 of relay SR3, conductor IOI, left contact I02 of relay TR, conductor I03, the primary of transformer TI20, and conductors 91 and 98 back to the supply terminal C.

When the contacts of relay TR are to the right and those of relay SR3 are in the released or midposition, the track transformer T00 only is active and the trackway then receives energy of the 60 coding over a circuit which may be traced from the supply terminal B through front contact II of relay AR, conductor II, the coding contact 50, conductor I05, released contact I08 of relay SR3, conductor I07, right contact I08 of relay TR, conductor I99, the primary of transformer T60 and conductor 98 back to the supply terminal C.

When the contacts of relay TR are to the right and those of relay SR3 are to the left, the trackway is supplied with energy of the 200 and the 00 codings simultaneously by way of the track transformers T209 and T90. The energizing clrcuit for transformer T200 extends from supply terminal B through front contact II of relay AR, conductor I I, coding contact 209, conductor 92, left contact 93 of relay SR3, conductor 94, right contact 95 of relay TR, conductor 96, the primary of transformer T290 and conductors 9? and 98 back to supply terminal C. The circuit through which the transformer T60 also receives energy may be traced from supply terminal B through front contact I I of relay AR, conductor II, coding contact 60, conductor I 95, released contact I06 of relay SR3, conductor I91, right contact I00 of relay TR, conductor I09, the primary of transformer T60 and conductor 98 back to supply terminal C.

When the contacts of relay TR are released and those of relay SR3 are to the left the trackway simultaneously receives energy of the 209 and the I20 codings. The circuit through which transformer T209 now receives energy may be traced from the supply terminal B through front contact I I of relay AR, conductor II, coding contact 290, conductor 94, released contact 95 of relay SR3, conductor 94, released contact 95 of relay TR, conductor 93, the primary of transformer T209, and conductors 91 and 98 back to the supply terminal C. The circuit through which transformer Tl20 is also energized may be traced from the supply terminal B through front contact II of relay AR, conductor H, the coding contact I20, conductor 99, left contact I99 of relay SR3, conductor I I0, released contact I2I of relay TR, conductors ti and I03, the primary of transformer Tl20, and conductors 91 and 98 back to the supply terminal C.

When the contacts of track relay TR are released and those of relay SR3 are to the right the trackway simultaneously receives energy of the I20 and the I59 codings. Under such conditions the circuit for the track transformer TI 20 extends from the supply terminal B through front contact II of relay AR, conductor I'I, coding contact I20, conductor right contact I00 of relay SR3, conductor IEII, released contact I02 of relay TR, conductor I03, the primary of transformer I20 and conductors 9i and 98 back to supply terminal C. The circuit through which transformer T60 also receives energy may be traced from the supply terminal B through front contact II, conductor I'I, coding contact 60, conductor I05, right contact H2 of relay SR3, conductor II3, released contact IM of relay TR, conductors H and IE9, the primary of transformer T60 and conductor 98 back to the supply terminal C.

When the contacts of relay TR are to the right and those of relay SR3 also are to the'right, the trackway simultaneously receives energy of all three of the 200, I and 60 codings. The circuit for transformer T299 extends from the supply terminal B through front contact II of relay AR, conductor II, the coding contact 200, conductor 92, right contact I I! of relay SR3, conductor H8, right contact IE9 of relay TR, conductors I22 and 95, the primary of transformer T200 and conductors 9'! and 98 back to the sup ply terminal C. The circuit through which transformer TI20 is energized may be traced from the supply terminal B through front contact I I, conductor H, the coding contact I20, conductor 99, right contact I00 of relay SR3, conductor IOI, right contact I02 of relay TR, conductor I03, the primary of transformer TI20 and conductors 91 and 98 back to supply terminal C. The circuit through which track transformer T60 likewise receives energy may be traced from supply terminal B through front contact II, conductor H, the coding contact 60, conductor I05, right contact I05 of relay SR3, conductor I01, right contact I08 of relay TR, conductor I09, the primary of transformer T60 and conductor 98 back to supply terminal C. Finally, when the contacts of both of the relays TR and SR3 occupy their released or mid positions, all three of the track transformers T60, TI20 and T200 are disconnected from the supply source BC and under this condition, of course, no coded energy is supplied to the track rails.

To facilitate explanation of the manner in which energy of two or more of the codings is combined in the track circuit, the diagram of Fig. 6 has been prepared as a counterpart of the previously described diagram of Fig. 2. When only two of the three individual codes shown in the upper portion of Fig. 6 are combined, the action is comparable to that explained in connection with the lower portion of Fig. 2. That is, the combination is a directly additive one, so

that during those times when two of thetrack transformers are simultaneously energized the energy level in the track circuit is double that when only one of the transformers is supplying energy.

- Similarly, when all three of the 60, 120 and 200 codings are simultaneously impressed upon the trackway, the resulting blocks of energy take the distinctive forms represented in the lower portion of Fig. 6. During those periods when only one transformer is active, the energy level is what may be termed normal; when two of the transformers are simultaneously active energy level is twice this normal value; and when all three of the transformers are simultaneously active the energy level is three times the normal value. In both of the diagrams in Figs. 2 and 6, it is assumed that the pulses of all three of the codes begin in synchronism. It will be appreciated, however, that this relation is not essential or necessarily typical, particularly since individual contacts of each of the coding devices CT of the wayside apparatus may or may not be arranged to provide the in-step starting, relation represented.

Considering now the train-carried equipment represented in Fig. '7 as being adapted to cooperate with the trackway apparatus of Fig. 5, its

cab signal 088' is, as mentioned previously, pro vided with eight separate lamps. tified by the characters A, R, L and S correspond in a general way to the devices of similar designation which form a part of the signal GS of the train-carried apparatus of Fig. 3. Theremaining four lamps designated by'the characters W, X, Y and Z are additional and are identified with the four added indications for which provision is made in. the extended wayside equipment of Fig. 5. v I

For the purpose of controlling the lighting circuit for the eight lamps of cab signal CS8, three decoding relays DR200, DRI20 and 'DRSB are provided. Each of these relays and the energizing circuit therefor may beof the same general character as that previously described in con v nection with the representation of Fig. .3. All receive energizing current from the secondary winding of a decoding transformer DT and the supply circuit of each includes a full wave rectifier 55.

Further included in the circuit of relay DR200 is a capacitor I24 and a reactor I25 which are so interrelated as to pass enough current to actuate the relay onlywhen energizingpulses of the 200 code frequency are received. from the trans-- former DT. In the case of relay DRI20, the circuit includes a capacitor I26 and a reactor I2'I designed to be resonant at the 120 code frequency and to energize the relay only when the decoding transformer passes energy pulses at the rate of 120 per minute. Likewise, the circuit of relay DR60 includes a capacitor I28 and a reactor I29 which are so interrelated as to pass enough current to actuate the relay only when energizing pulses of the'60 code frequency are received from the transformer.

The remaining portions of the train-carried apparatus of Fig.7 are duplicates of the correspondingly identified equipment shown in Fig. 3 and which has been described in detail previously. Hence it will suflice to say that the receiver 3631 inductively picks up energy from the track rails I and 2; filter 38 transmits this energy if it is of the proper carrier-wave frequency such as the assumed 100 cycle-per-second value; and the amplifier 39 strengthens this transmitted energy, rectifies the component alternating current waves thereof, and impresses an amplified measure of the modulation or coding thereof uponthe master transformer MT. This transformer, in turn, controls the two push-pull connected amplifier tubes M and 42 which operate in the primary circuits of the decoding transformer DT. And finally, this decoding transformer impresses upon the energizing circuits of The four iden the decoding relays DR an alternating current voltage of a frequency which is the same as is that of the trackway code by which the primary current pulses are initiated. In the particular system disclosed in Figs. -7 this secondary voltage thus will have individual frequencies of 60, 120 or 200 cycles per minute.

Depending upon the frequency of the output voltage of the decoding transformer DT, the three 1 relays DR selectively complete one or another of the lighting circuits for the eight'lamps of the cab signal CS8. When the received energy from the trackway is of the 200 coding only, the contacts of decoding delay DR200 are picked up and those of relays DRIZO and DR60 are released. Under this condition lamp A of the cab signal receives lighting current over a circuit represented as extending from the positive terminal of a supply source through front contact I3I of relay DR200, conductor I32, back contact I33 of relay DRI20, conductor I34, back contact I35 of relay DR60, conductor I36, the signal lamp A and conductor I31 back tothe negative supply terminal of the mentioned source.

When train control energy of the I20 coding only is received from the trackway the contacts of decoding relay DRIZI] are picked up and those of relays DR200 and DR60 are released. Under this condition lamp R of the cab signal receives lighting current over a circuit which extends from the positive supply terminal through back contact I3I of relay DR280, conductor I38, front contact I39 of relay DRI20, conductor I40, back contact I4I of relay DR60, conductor I42, the lamp R, and conductor I3'I back to the negative supply terminal.

When energy of the 60 coding only is received from the trackway, the contacts of decoding relay DRISI! are picked up and those of relay DR200 and DRI20 are released. Under this condition lamp L of the cab signal is lighted over a circuit extending from the positive supply terminal through back contact I 3I. of relay DR200, conductor I38, back contact I39 of relay DRI20, conductor I43, front contact I44 of relay DR60, conductor I45, the lamp L and conductor I3I,,back to the negative supply terminal.

In the event that the train-carried equipment of Fig. 7 fails to receive coded energy from the trackway, the contacts of all three of the decoding relays are released and the cab signal lamp. S then is lightedover a circuit extending from the positive supply terminal through back contact I3I of relay DR200, conductor I38, back contact I39 of relay DRI20, conductor I43, back contact I44 of relay DR60, conductor I46, the lamp S and conductor I31 back to the negative supply terminal.

When the received energy is of the composite 20060 energy pulse per minute coding, decoding relay DR200 responds to the 200 pulse component thereof and relay DRGG responds to the 60 pulse per minute component of the energy, the action in both cases being the same as were the 200 and the 60 codings to be received individually. Under the stated conditions, therefore, the contacts of both of the relays DR200 and DR60 are picked up and those of relay DRI20 are released. Cab signal lamp W now receives lighting current over a circuit which extends from the positive supply terminal through front contact I3I of relay DR200, conductor I32, back contact I33 of relay DRIZIJ, conductor I34, front contact I35 of relay DRBO, conductor I48, the lamp W and conductor I31 backto the negative supply terminal.

Similarly, when the received energy is of the composite 200120 pulse per minute coding, the contacts of the relays DR200 and DRI20 are picked up and those of relay DRBI] are released. Under this condition cab signal lamp X receives lighting current over a circuit which extends from the positive supply terminal through front contact I3I of relay DR200, conductor I32, front contact I33 of relay DRI20, conductor I49, back contact I50 of relay DR60, conductor I5I, the lamp X and conductor I31 back to the negative supply terminal.

Likewise, when composite train control energy of the I2060 coding is received, the contacts of the relays DRIZO and DRBO are picked up and those of relay DR200 are released. Under this condition cab signal lamp Y is lighted over a circuit extending from the positive supply terminal through back contact I3I of relay DR200, conductor I38, front contact I39 of relay DRI20, conductor I40, front contact I M of relay DR60, conductor I52, the lamp Y and conductor I31 back to the negative supply terminal.

Finally, in the event that composite train control energy made up of all three of the 60, I20 and 200 codings is received by the equipment of Fig. 7, the contacts of all three of the decoding relays DR200, DRI28 and DRIiIl are picked up to produce a lighting on the part of the cab signal lamp Z. The lamp energizing circuit may be traced from the positive supply terminal through front contact I3I of relay DR200, conductor I32, front contact I33 of relay DRI20, conductor I49, front contact I50 of relay D360, conductor I53, the lamp Z and conductor I31 back to the negative supply terminal.

From the foregoing it will be seen that I have provided a novel and improved form of organization of railway traffic controlling apparatus into systems wherein cab signals or other governing devices carried aboard a train vehicle are con-,

tinuouly controlled by energy coded in accordance With advance conditions and transmitted to the vehicle through the track rails. One practical advantage of my new multiple indication system is that it posseses increased flexibility, comprehensiveness and range of application and readily is capable of providing as many different indications aboard the train as may possibly be desired.

Another advantage is that the extended number of cab signal indications is obtainable from a restricted variety of trackway current codes. Thus, in the embodiment of my invention shown in Figs. 1-3, a total of fourindications are provided from only two different coding rates by selectively using them in the form of two singles, one none, and one double. Likewise, in the embodiment of my invention disclosed in Figs. 57, eight indications are obtained from only three codes selectively used in the form of three singles, one none, three doubles, and one triple. Hence, it will be evident that by further multiplying the code frequency any desired number of indications are readily obtainable. Thus, if four modulation frequencies are used, a total of 16 indications aboard the train can be had from four singles, one none, six pairs, four triplets, and one combination of four.

By eliminating from the decoding apparatus the usual mechanical code following relay and providing in its stead the electronic tubes 4| and 42, the receiving equipment of my improved system is capable of following code pulses of unlimited rates. The only limitation in selecting the rates is that they be sufficiently.separated'tdassure against confusion thereof by the tuned circuits of the decoding relays. In practice, margins such as are represented by the spread between the and the 180 code per minute rates described in connection with the system of Figs. 1-3, and the 60, and 200 code per minute rates described in connection with the system of Figs. 5-1 are found to be amply wide.

Ordinarily the tuning curves are sharpest on the side toward the lower modulation frequencies. However, since rather large and heavy apparatus is required to tune the lower code frequencies some saving in equipment cost may be effected by choosing modulation frequencies of a somewhat higher order than are customary, such as, for example, 100, and 320 cycles per minute. Another advantage of such choice is that with the same or even smaller apparatus the circuits are capable of more sharp tuning and hence a more distinct separation between codes then is obtainable.

A still further practical advantage of the herein disclosed expedients of my invention is thatthe desired extension in the number of cab signal indications is accomplished by relatively simple additions to and without fundamental changes in the equipment of existing systems of coded cab signalling. In all instances, as has been seen, the required spread between code rates may be 010 tained from a choice of modulation frequencies which are sufficiently near to the values at present used to' occasion noserious operating or manufacturing difficulties. 'In the wayside equipment, the code transmitters, the track transformers, and the control relays are all of standard design, and in the train-carried apparatus use likewise is made of equipment of commercially standardized character. Moreover, to arrange the circuits and organize the apparatus in the novel and advantageous manner proposed by my invention entails few if any practical difficulties.

Although I have herein shown and described only two forms of railway traffic controlling apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. Railway traffic controlling apparatus comprising means for supplying the trackway with energy coded at one or another of a plurality of different rates individually or at a plurality of said rates compositely, and traffic-governing means responsively controlled by said trackway energy for displaying a distinctive indication for each individual coding thereof and for each com posite coding thereof.

2. In combination, a stretch of railway track, means for transmitting energy to the rails of said stretch, means for coding said energy individually at one or another of a plurality of different rates or compositely at a plurality of said rates, means for receiving from said rails a measure of said coded energy, decoding relays controlled by said received energy and selectively responsive both to the individual coding and'to the compos ite coding thereof, and signals selectively controlled by said relays. I

3. In a railway trafiic controlling system, the combination with a stretch of track of a"s'ource of electrical energy, a plurality of circuits through which said source may be connected to the rails of said stretch, means for coding at a distinctive rate the energy which each of said circuits transmits, means responsive to predetermined conditions for selectively rendering one or another of said circuits individually active or a plurality of said circuits compositely active, and traiiic-governing apparatus controlled by said trackway energy and selectively responsive to each individual coding thereof and to each composite coding thereof.

4. In combination, a stretch of railway track, a source of current, a coding device having a plurality of circuit-making-and-breaking contacts which operate at different rates, a plurality of circuits each of which includes a different one of said contacts and through each of which current from said source may be supplied to the rails of said stretch, means for selectively rendering active-one or another of said contact-including circuits individually or a plurality thereof com positely, and traffic-governing apparatus controlled by the trackway energy and selectively responsive to each individual codin'g'thereof and'to each composite coding thereof.

5. In a railway traffic controlling system, the

combination of a section of track, a plurality of circuits through which energy may be supplied to the rails of said section, a coding device having a plurality of circuit-making-and-breaking contacts which operate at different rates and a different one of which is respectively included in each of said circuits, trafiic-controlled means for selectively rendering active one or another of said circuits individually or a plurality thereof simultaneously, and traffic governing apparatus controlled by the combined energy which said rails receive from said circuits.

6. In a railway traffic-controlling system, the combination of a section of track, a pair of circuits through which energy maybe supplied to a;

the rails of said section, a coding device having a pair of contacts which operate at different rates and a different one of which is respectively included in each of said circuits, track and auxiliary relays controlled in accordance with traffic conditions, means including contacts carried by said relaysfor selectively rendering one or the other of said circuits individually active or both of said circuits simultaneously active, and trafiic governing apparatus controlled by the combined energy which said rails receive from said circuits.

7. In combination, a forward and a rear section of track, a plurality of circuits through which energy may be supplied to the rails of said rear section, a coding device having a plurality 1 combination of 1 a section of track, a circuit through which energy may be transmitted to the rails of 'said section, a plurality of track transformers having secondary windings serially included insaid circuit, means forenergizing one or another of said'transformers individually or .a plurality thereof simultaneously, and traific governing apparatus controlled by the combined energy which said rails receive from said transformers by way of said circuit.

9. In combination, a section of railway track, a circuit through which energy may be transmitted to the rails of said section, a plurality of track transformers having secondary windings serially included in said rail supply circuit, a circuit for supplying each of said transformers with energizing current which is coded at a distinctive rate, means for rendering one or another of said transformer supply circuits individually active or a plurality thereof simultaneously active, and traflic governing apparatus controlled by the combined energy which said rails receive from said transformers by way of said rail supply circuit.

10. In a coded train-control system, the combination of a circuit through which energy may be transmitted to the trackway, a plurality of track transformers having secondary windings serially included in said supply circuit and arranged to be energized individually, a by-passing circuit associated with each transformer and arranged to lower the impedance to the flow of trackway current which that transformer offers when it is not transmitting energy, and trafiic governing apparatus controlled by the combined energy which the trackway receives from said transformers by way of said supply circuit.

11. In a coded train-control system, the combination of a circuit through which energy may be transmitted to the trackway, a plurality of track transformers having secondary windings serially included in said supply circuit and primary windings arranged to be energized individually, an impedance element bridged across the said secondary winding of each of said transformers for the purpose of lowering the impedance to the flow of trackway current which each 'of those transformers offers when it is not transmitting energy, and trafiic governing apparatus controlled by the combined energy which the trackway receives from said transformers by way of said supply circuit.

12. In a coded train-control system, the combination of a supply circuit through which energy may be transmitted to the trackway, a plurality of track transformers having secondary windings serially included in said supply circuit, means for energizing each of said transformers individually, a lay-passing circuit for each transformer, means for rendering each of said bypassing circuits active at all times except when the transformer with which it is associated is transmitting energy, and traffic governing apparatus controlled by the combined energy Which the trackway receives from said transformers by way of said supply circuit.

13. In combination, a rail supply circuit through which energy may be transmitted to the rails of a track section, a plurality of track transformers having secondary windings serially included in said rail supply circuit and primary windings, a source of energy, a circuit system for connecting said primary windings to said source, relay means for determining which and how many of said primary windings are so connected, a by-passing circuit for shunting each of said primary windings, contacts operated by said relay means for completing each of said by-passing circuits when the associated primary winding is disconnected from said source, and trafiic govsaid two contacts respectively connect said two i transformers to said source when those contacts are in one of their said two positions, circuits through which said contacts respectively by-pass the said transformers when the contacts are in the other of their said two positions, a capacitor which shunts each transformer during each shift of the associated coding contact from one position to the other, and traflic governing apparatus controlled by the combined output energy of the said series connected windings of said two transformers.

15. In a railway traflic controlling system, the

combination of means for supplying the trackway with energy coded at one or another of a plurality of different rates individually or at a plurality of said rates compositely, means on a train for receiving a portion of said trackway energy, a decoding transformer controlled by said received energy and arranged to be supplied with a surge of primary current upon the i occasion of each code pulse of that energy whether of an individual coding or of a composite coding, a plurality of decoding relays selectively responsive to the frequency of the output voltage of said transformenand train-governing signals selectively controlled by said decoding relays.

16. In a railway traffic controlling system, the combination of a train-carried receiver for picking up coded energy from a trackway, a plurality of decoding relays, means responsive to the frequency of code pulse recurrence of said received energy for effecting an actuation of one or another of said decoding relays individually when that energy has an individual frequency coding and of two or more of the relays simultaneously when that energy has a composite or multi-frequency coding, and train-governing signals selectively controlled by said decoding relays.

17. In combination, a trackway which is supplied with energy of one or another of a plurality of different codings individually or of two or more of said codings compositely, a plurality of decoding relays supplied with actuating current one at a time in response to individual codings of said trackway energy and a plurality at a time in response to composite codings thereof, a plurality of signal-energizing circuits, and contacts carried by said relays for selectively completing said circuits.

l8. Train-carried signalling apparatus comprising a decoding transformer, circuit means through which said transformer receives codefollowing pulses of primary current under the control of energy received from a trackway, decoding relays individually actuated by the output energy of said decoding transformer when it is controlled by individually coded energy and simultaneously actuated when the transformer is controlled by compositely coded energy, a plurality of train-governing signals, a system net work of completable energy-supply circuits for said signals, and contacts carried by said decoding relays for selectively completing said circuits.

19. In a railway signalling system, the combination of means for receiving coded energy from the trackway, means for converting said energy into an alternatingcurrent Voltage of an amplitude which is proportional to the number of codes instantaneously present in said track- Way, an electronic tube having a control grid which receives-said voltage, a decoding transformer energized through a circuit which includes said tube, decoding relays selectively actuated by theoutput energy of said transformer, and traffic-governing signals selectively controlled by said decoding relays.

20 In a railway signalling system, the combi-- nation of means for receiving coded energy from the trackway; an amplifier unit anda deeperating master transformer arranged to demodulateeach pulse of saidenergy into code frequency only, a pair of electronic tubes having major electrodes and control-grids which receive reversely related portions of saidvoltage, a decoding transformer provided with a pair ofcooperating 'primary energizing circuits each of which includes thesaidmajor electrodes of one of said tubes, and trafiic-governing means selectively controlled by the output energy of saiddecoding transformer.

PAUL N; BOSSART. 

